The invention lies in the field of electrical connecting elements. Such electrical connecting elements are wiring systems for an arrangement of active and/or passive electrical or electronic components. Examples of electrical connecting elements are printed circuit boards, high density interconnects (HDIs), flex-prints, interposers etc. The invention specifically relates to electrical connecting elements with embedded resistors, as well as their manufacture.
Printed circuit boards, for example with electrical resistors embedded in a network-like manner are known. It is known for example to enclose a resistance layer in printed circuit board materials, from which a network of electrical resistors may be produced by way of selective etching. Such a resistance layer consists for example of a nickel alloy. However, there exists the problem of the absence of etching means selectivity, on etching the resistance layer or the copper layer which adheres thereto, via which the contacting of the resistors is effected. Furthermore, with known printed circuit board materials, a nickel layer bears directly on a plastic substrate layer. The adhesion properties of nickel alloys to plastic layers are, however, not very good. For this reason, the resistance layer may detach in unfavourable cases. Furthermore, due to manufacturing technology, only a limited thickness region is available, and one may not manufacture arbitrarily thin nickel layers for the mentioned printed circuit board materials.
For this reason, it is the object of the invention to provide a method for manufacturing electrical connecting elements, as well as an electrical connecting element, which overcomes the disadvantages according to the state of the art, and which in particular makes do without a large-surfaced transition between an insulator layer and a nickel layer.